This invention relates to a border for a display device as defined in the preamble of claim 1.
When an observer views a substantially planar image (such as that formed on a television screen or a painting) the brain identifies a number of visual cues which lead to the realisation that a substantially planar image is being viewed. Such flatness cues tend to contradict depth cues, such as perspective, which may be present in the image itself.
In order to make such an image appear more three dimensional, a body forming a border as described in the first paragraph may be used. Such a body is disclosed in U.S. Pat. No. 3,582,961. In this known border the first and her patterns are formed by dark stripes on a transparent lamina. When viewed together in transmission the patterns produce a resultant Moire interference fringe pattern. When this known border is superimposed upon the peripheral edges of a pictorial image displayed on, for example, a projection screen, the flatness cues associated with the edges of the flat screen are suppressed. An illusion of depth in the image is created from monocular depth cues (e.g. perspective and obscuration) which may be present in the flat image. Such depth cues are discussed in, for example, the paper by Harold Schlosberg in the American Journal of Psychology, Volume 54, Number 4 October 1941 pp 601-605.
There are a number of disadvantages associated with the body of U.S. Pat. No. 3,582,961. For example, the patterns are one dimensional, so that motion parallax will only occur when an observer moves his or her head in a specific direction. The patterns are fixed and it is therefore difficult to alter the apparent distance between the plane of the border and the resultant pattern, other than by substitution of the original body with a different body or by physically moving one pattern.